Liquid crystalline polymers are known, among thermoplastic resins, as the materials having excellent dimensional accuracy, vibration damping property, and flowability, which generate very few burrs during molding, and very little gas. By utilizing these characteristics, the liquid crystalline polymers have been adopted in large quantities as the materials for varieties of electronic parts.
In particular, with the increase in performance of electronic equipment in recent years, there have appeared the needs of the times for connectors having high heat resistance (the improvement in productivity supported by packaging technology), high density (multicore), and miniaturization. By taking advantage of the above liquid crystalline polymers, the liquid crystalline polymer compositions reinforced with glass fiber have been adopted as connector materials, (JP-A 9-204951).
However, in recent years, by the further movement toward “lighter and more compact” connectors, there have arisen the problems of the generation of warpage after molding and during reflow-heating owing to the insufficient rigidity resulted from insufficient wall thickness of the molded product and to the internal stress generated by inserting metal terminals, which causes defective soldering with circuit-board. That is, regarding the conventional strengthening only by glass fiber, there has arisen a problem in that a thin wall portion can not be filled with resin, or insert terminals are deformed due to pressure during molding by the increased additive amount of glass fiber for increasing the rigidity.
To solve the warpage problem, molding methods were devised and, from the standpoint of material, filling a specific plate-like filler has been proposed, (JP-A 10-219085 and JP-A 2001-106923).
For ordinary connectors (electronic parts) available in the market in abundance, the dimensional accuracy and warpage of products can be controlled by designing the gate position so as to keep the symmetry during molding, and the products having smaller warpage are further obtained by using a low-warpage material which has already been proposed.
However, with the increased complexity in the shape of electronic parts in recent years, there has been required to provide asymmetric electronic parts that has no symmetry on any of the axial plane XY, axial plane YZ, and axial plane XZ of molded product. Typical samples of that type of asymmetric electronic parts are memory module connectors having a latch structure (having fixing claw at each end), such as DDR-DIMM connector. In particular, since a memory module connector for notebook personal computer has a latch structure for connection and has a notch for positioning, the connector becomes a highly complex shape.
Different from the ordinary connector (symmetric electronic parts) which is symmetry on any of the axial plane XY, axial plane YZ, and axial plane XZ of molded product, the above asymmetric electronic parts have no symmetry, and thus the asymmetric electronic parts have a limitation in improving warpage from the standpoint of molding procedure. Furthermore, an asymmetric electronic parts having a complex shape results in complex orientation of resin and filler within the molded product, which raises a problem of further difficulty in suppressing warpage by required higher flowability, and it impossible to obtain satisfactory product from the conventionally-proposed low-warpage material.